So you draw what your heart desires, then print it at 100% actual size.

A step bit and a centerpunch are handy items to have for this project. we'll see the Scrollsaw a bit later...

Not seen in the next pic very well: First cover the sheet stock with contac paper. When you go to remove your layouts, you'll be happy you did. Get some spray adhesive and fix the prints to your chosen material:

Then mark and drill the holes. Do this with the parts still in as large as possible chunks. This will minimize fixturing, you can save a bunch of time doing this. Then cut out your parts using a Scrollsaw:

TOP SECRET: Use these, and only these, blades:
Vermont American #30423
(5" long, 11.5 teeth per inch, .045 blade depth, .017 thick.)
Cuts ABS and PVC like butter. Slow speeds are best for ABS.

Your freshly cut parts. If you're proud of your work, take pictures and show the world. Maybe show others how you did it:

Do a test assembly to make sure no fitting is needed.
The worst time to find out you needed to file an edge is after it has nice sticky glue all over it.
If everything fits, grab the glue or fasteners.

Maybe a coat of paint and some doodads:

You can make just about any bracket or other part you might need this way.

I made most of this gun this way...
This gun has a high-speed Systema motor, 170 spring, metal bearing spring guide, metal bushings, reinforced piston/head, fully ported cyl, and a Stainless steel cushioned cyl head.
How does this gun work? Terrible on semi. The bb will go about two feet before dropping. On full auto, yeehaw! It will spit a solid stream of hard-hitting pellets with very acceptable accuracy for CQB.

You're doing some pretty amazing stuff KB. How do you work out bend allowance for your sheet metal work? I use SolidWorks which does my bend allowance compensation.

I haven't done this manually though. Usually I end up bending my part then drilling the holes so everything lines up right. Even with bend allowance it's not hard to screw up holes drilled before the bend. Bend allowance is bend radius dependant which is hard to control with small shop tools. I guess you can do a bunch of test bends with your equip with predrilled mat'l and do some measurements to see where everything ends up to predict how your finish parts turn out.

In Sheet metal engineering, the term k-factor has the following meaning:

During bending the inner surface of the bend is subjected to compression while the outer surface is subjected to tension. However there is a layer in between which is free from any forces and thus its length remains the same. This is called the neutral axis ( N.A ). The radius of this layer of metal is called the neutral bend arc radius ( NBAR )and is defined as the inside bend radius plus a percentage( K-factor ) of the metal thickness.

And EASY-TO-UNDERSTAND info here:http://www.sheetmetaldesign.com/Whit...wance/Body.htm
I avoid all this by not bending if I don't have to. The curved parts of the foregrip lower areas are 1/2" PVC, sawn in half and molded in with marine epoxy stick.
I have a sheet plastic bender, I bought it to make a Barret M82 housing, just haven't set up yet. I will need to compute the bends for the outer housing of this baby:

And there isn't one scrap of sheetmetal. It's all expanded PVC, or Komatex, by trade name. It cuts/glues easily with PVC pipe cement, molds with marine epoxy or wall spackle, and as you can see, you can make about any shape from it. The finished parts are VERY durable.

By the way, here's the drawing of the "Shrike" parts:http://www.air-sharp.com/shrike062707.dwg
Just print the first layout tab like it is, you'll get 100%-size parts to use. Some parts are made from .247"/6mm material, others are .120"/3mm material, available at:

Until recently the prices of airsoft guns in Canada (multiple times the US price) translated to a reluctance to cut them up for parts and projects like these. With many more affordable guns becoming available, I suspect we will see more of these types of projects being undertaken.

__________________

"Sex is one of the 9 reasons for reincarnation, the other 8 are unimportant." Henry Miller

YAY!
Don't even use patterns, just start cobbling. There's a 1919 out there on the internet with the back end of an AK-47 sticking out of it. And it's gotten zillions of fans. Don't be afraid of stoopid*.

Make your own gun creation up- if you're thinking of re-creating a movie or comic, videogame, manga, etc., weapon, get in line.
Somebody out there is spending more time than you on one, I guarantee.Come up with your own backstory.
Build a world around something like this, somebody might start throwing money in your coffee.

*I never once went looking for a smart girlfriend.
"A man's gotta know his limitations" -Dirty Harry